A prototype of an advanced fiber-optic remote thermoluminescence dosimetry (TLD) sensor system will be developed for applications in in vivo and in situ dosimetry. It features near-infrared laser beam heating with microprocessor-controlled operation, digital processing and thin, flexible, mechanically durable, and re-usable (without removing from inside the phantom or the patient) quartz fiber sensor probes for gamma, beta and neutron dosimetry in clinical applications. These probes can also be sterilized for re-use with different patients. The new technology is based on heating, with a near-infrared laser beam, small amounts of thermoluminescent phosphor material on the tip of quartz optical fiber sensor probes. TLD phosphors to be used include CaSO4:Mn, MgB407:Tm (for near tissue-equivalent applications), and CaF2:Tm for fast neutron-gamma discrimination. The heating beam will be provided by a closed-loop controlled low cost semiconductor laser emitting at approximately 840 nm. Individually calibrated sensor probes containing a very small amount of a suitable commercial TLD phosphor in their tips will be fabricated and tested in simulated in vivo applications. They will be up to several meters in length and less than 2 nm in diameter.